Tertiary amine oxides are widely used commercially as organic surfactants. Such surfactants have properties that make them very useful in shampoos, hair conditioners, dish and laundry detergents, fabric softeners and the like. In these applications, the tertiary amine oxides are employed as aqueous solutions. More recently, however, there has been interest in the use of tertiary amine oxides as additives for thermoplastic resins. In these new additive applications it is important to have a high solids level, preferably a solid tertiary amine oxide containing a minimal amount of volatile solvents to avoid difficulties in removing the solvent during the compounding and processing operations.
Nitrosamines have been reported as minor by-products in the conventional preparation of tertiary amine oxides using aqueous hydrogen peroxide. Although the amount of nitrosamine is very small, on the order of only a few hundred parts per billion (ppb), this small amount renders the amine oxide unsuitable in many applications that involve human contact. This is because nitrosamines are reported to be carcinogenic and/or mutagenic. Hence, a need exists for a method for making tertiary amine oxides in high conversion and yield and at a fast reaction rate while at the same time producing tertiary amine oxide products that are solids at ambient temperatures and that are substantially free of nitrosamines (i.e. have a level of N-nitrosodimethyl amine of less that about 100 ppb). The present invention provides such a process.